Respiratory aid apparatus and method

ABSTRACT

A system and method are disclosed for the provision of assisted breathing by the delivery of a controlled pressurized airflow to the pulmonary airway of a user with breathing disorders. The system comprises a source of compressed respiratory gas ( 112 ), a user interface unit ( 115 ) including at least one Venturi device ( 120 ) and a thin flexible tubing ( 116 ) connecting between the source of high pressure gas ( 112 ) and the Venturi device. The system and method provide a regulated and controlled flow of air to the user ( 105 ) in accordance with the user needs. The invention further discloses a novel small light-weight user interface for replacing prior art breathing masks.

RELATED APPLICATION

This application claims priority to International Application NumberPCT/IL2003/000599 filed on Jul. 22, 2003, which claims priority to U.S.Provisional Patent Application Ser. No. 60/397,042, filed Jul. 22, 2002the contents of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention generally relates to a respiratory aid for thealleviation of breathing and airway disorders, and more specifically toa respiratory aid comprising a Venturi air pump.

2. Discussion of the Related Art

The present invention relates to respiratory disorders in which externaldevices are used for delivering respiratory gas to assist spontaneous orforced breathing. Although the invention relates in particular to sleepapnea, the device and method disclosed in the following are not limitedto this particular use and can be utilized for the alleviation of otherrespiratory disorders as well.

Sleep apnea is a disorder characterized by full or partial cessation ofbreathing during sleep. Apnea is defined as an interruption in breathing(air-flow into the lungs) for at least ten seconds, accompanied by adecrease in oxygen saturation. Hypopnea is a milder form in which thereis a 50% decrease in air-flow for more than ten seconds. The number ofincidents in which there is an interruption in breathing define theseverity of the disorder. Patients suffering from sleep-associated apneamay have as many as 300-500 such interruptions in air-flow per night,each lasting 30-40 seconds. Obstructive Sleep Apnea (OSA) is the mostcommon apneic disorder stemming from a mechanical obstruction in theupper respiratory airways during sleep. It is caused by recurrentblockage or narrowing of the airways during sleep and reduction inoxygen saturation.

Following the period of cessation of breathing, an abrupt, but brief,waking occurs caused by the urgent need for oxygen. This requirement ismet by a single powerful inhalation, usually accompanied by a loudsnore. Since this phenomenon occurs many times per night, it causes afragmented, and unsatisfactory, sleep pattern. As a result of thefrequent oxygen deprivations during the night, the patient willexperience tiredness and lassitude during the daytime, sometimesresulting in uncontrolled sleep episodes during waking hours. Theseverity of the sleep apnea is usually expressed by the average numberof complete or partial blockages per hour.

A significant number of sleep apnea patients have been found to sufferfrom enhanced cardiovascular morbidity. In addition, sleep apnea hasbeen shown to be a risk factor for: systemic hypertension, pulmonaryhypertension, ischemic heart disease, acute myocardial infraction, andbrain infarction. The daytime sleepiness and tiredness, associated withthe fragmented sleep pattern, expose these patients to additionaldangers such as traffic accidents and work-associated accidents.

The present invention addresses other breathing disorders as well. Theseinclude: intensive care patients requiring assisted breathing,post-operative patients, asthmatic patients, patients with emphysema,patients with severe lateral sclerosis, patients with chronic heartfailure, multiple sclerosis patients, and other breathing-associateddisorders.

People with moderate to severe OSA are usually treated with CPAP(Continuous Positive Airway Pressure). The CPAP device is essentially anair pump connected by flexible tubing to a mask worn by the patient.This forced air flow, the pressure of which can be regulated dependingon the severity of the apnea in each individual, keeps the airways fromcollapsing, thus preventing the interruptions which result in the apneicepisodes. A typical CPAP system is illustrated in FIG. 1A. It comprisesan air blower 1 which supplies a continuous flow of compressed air atrelatively low pressure, usually in the range 2 to 20 mbar (20-200 mmH₂O). The air stream is forced through the flexible wide-bore (20-25 mm)tubing 2 to the mask assembly 3 placed on the patient's face and held inplace by a head-encircling elastic straps 4. In order to keep a positivepressure inside the CPAP mask, the mask must have a peripheral seal.There exist a variety of CPAP masks varying from full-face maskscovering both nose and mouth as mask 3 of FIG. 1A, through nasal maskswhich cover only the nose, and include nostril assemblies, as shown inFIG. 1B, in which the air is directly administrated to the nostrils. Thenostril assembly of FIG. 1B is held by a curved plastic holder 6 affixedto the patient's head for supporting tubing 2. Tubing 2 terminates witha rigid short tube 7 connecting between tubing 2 and nostril piece 5inserted into the patient's nostril.

The CPAP device has been proven to be successful in preventing breathingobstruction during sleep but it suffers from a number of drawbacks,associated mainly with discomfort to the user, as detailed in thefollowing:

-   -   1. A CPAP apparatus is cumbersome to use because the mask and        its straps are uncomfortable to wear. The mask assembly,        together with the thick air pipe, limits the sleep positions of        the patient and confines his/her ability to turn in their sleep.        Since turning during sleep is an activity not controlled by the        patient, the CPAP device itself may cause such discomfort as to        wake the patient, and/or reduce the quality of sleep.    -   2. The apparatus requires connection to a power supply, which        limits the mobility of the patient, and interferes with        activities when an electrical outlet is unavailable (flights,        camping, etc).    -   3. Since the device supplies a constant positive airflow through        the mask, the user is forced to exhale at a pressure greater        than the incoming flow of air in order to overcome the blower        pressure. This is particularly true for a CPAP having a        full-face mask, but also for situations with a nasal mask when        the patient exhales through the nose. This necessity runs        counter to the natural breathing rhythm during sleep, and        requires adaptation.    -   4. When using the more common nasal mask, the patient is often        forced to exhale through the mouth, resulting in dryness of the        oral cavity during the night.    -   5. Since the air flows under relatively low pressure, it must be        forwarded in large diameter pipes. If a smaller diameter pipe is        used, it will decrease the air pressure intended for breathing        and the apparatus will lose its efficiency.    -   6. When temporarily there is no need for the device, it is the        practice to disconnect the device from the user due to the        discomfort of wearing the mask and the restrictions to the user        movements when connected to the device. When the need returns,        the device has to be fitted again.

Thus, in spite of the undoubted benefit of CPAP devices in preventingapneic episodes, it was found that many patients tend to stop using thedevice after a period of time due to discomfort.

Accordingly, it is the general objective of the present invention toprovide device and method that supply the necessary positive airflow toprevent airway collapse while overcoming the disadvantages of presentCPAP devices.

In particular, it is one object of the invention to provide arespiratory aid apparatus that minimizes discomfort to the user, islight in weight, is mobile, and can be operated by batteriesindependently of electric current supply.

It is another object of the invention to provide a respiratory aidmethod and system that allow control of airflow according to the needsof the user and that allow regulating the airflow during the respirationcycle, making the breathing process more normal and comfortable.

Yet it is another object of the invention to provide a respiratory aidmethod and system that can be easily turned on or off and that whenturned off allows for a normal breathing with no need to disconnect theuser from the system.

Yet it is a further object of the invention to provide a respiratory aidsystem and method that not only delivers airflow to the user duringinhalation phase but further provides active removal of air from theuser airways during the exhalation phase.

A further object of the invention is to provide a respiratory aidapparatus that can be used with any currently available breathing mask,and is small, effective, easy to manufacture and is of low cost.

Yet a further object of the invention is to provide a novel userinterface unit that can replace currently available breathing masks, andis small, flexible, can be easily adjusted to fit the user and is muchmore comfortable than currently available masks

SUMMARY OF THE INVENTION

In accordance with the above objectives, the present invention providesa respiratory aid system and method for providing a user withrespiratory gas at a pressure which will keep the airways open foravoiding breathing difficulties due to mechanical obstruction and/ordisease processes. The proposed system overcomes the drawbacks of priorart systems, minimizes discomfort to the user and allows for accurateregulation of the airflow administrated to the user airways.

A broad aspect of the invention is the use of a Venturi device,incorporated within a user interface unit in fluid communication with auser's airways, for administrating a controlled pressure of air to auser.

Another aspect of the invention is a respiratory aid apparatus foradministrating a controlled flow of respiratory gas to a user's airways.The apparatus comprises a source of a high pressure respiratory gas; auser interface unit, including at least one Venturi device, locatedproximal to the user's air intake organs in fluid communication with theuser's airways; and a low cross-section flexible tubing connectingbetween the source of high pressure respiratory gas and the userinterface unit. The Venturi device comprises a hollow member, defining acentral space open at both sides, and an inlet port opening into thecentral space. One end of the Venturi device is open to surroundingambient air and the second open end is directed toward the user airways.The inlet port of the Venturi device is configured to direct compressedgas entering the central space toward the user airways. The source ofthe high pressure respiratory gas may be an air compressor or a gascylinder containing a high pressure of air, oxygen enriched air or pureoxygen. In accordance with the invention, the source of high pressurerespiratory gas is provided with a regulator for regulating the outputpressure of said source. Preferably, the apparatus is further providedwith at least one sensor for detecting the respiratory cycle of the userand with at least one controller interposed between the source of highpressure respiratory gas and the user interface unit for controlling thepressure of compressed gas entering the Venturi device. In accordancewith one embodiment of the invention, the Venturi device may furthercomprise a second inlet port opening into said central space, configuredto direct compressed gas entering the central space toward the end opento ambient air for assisting removal of air from the user's airways, andwith a controllable valve for directing the compressed air alternatelyto the first inlet port during inhalation phase and to the second inletport during exhalation phase. The apparatus may be used with anyavailable breathing mask.

A further aspect of the invention is a gas delivery user interface unitof reduced size for enhancing the user's comfort, that can replace anyprior art breathing interface. The user interface unit includes at leastone Venturi device. In accordance with one embodiment, the userinterface unit comprises two Venturi devices provided with a nasaladaptor to be inserted into a nostril of the user. The two Venturidevices may be mounted on a mouth piece or on a connecting member to beplaced between the upper lip and the nose of the user wherein the thintubing delivering the compressed gas into the user interface may serveas strapping means for strapping the unit to the head of the user.

A further aspect of the invention is a method for supplying a controlledpressure of respiratory gas to a user, the method comprising: deliveringa high pressure respiratory gas via a thin tubing to a user interface influid communication with the user's airways, the user interface ishaving an inlet port connectable to said thin tubing; and acceleratingthe high pressure respiratory gas upon entering the user interface bymeans of a Venturi device located at the inlet port of the userinterface, the Venturi device is configured to direct flow of compressedair toward the user's airways, the Venturi device is having an end opento surrounding ambient air; thereby pumping ambient air into the userinterface. The method further comprises controlling the pressure of thehigh pressure respiratory gas delivered to the user interface. Themethod may further comprise stopping the delivery of high pressurerespiratory gas during exhalation phase.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be understood and appreciated more fully fromthe following detailed description taken in conjunction with thedrawings in which:

FIG. 1A is schematic illustration of a prior art CPAP apparatus and CPAPmask;

FIG. 1B is a schematic of illustration of another prior art CPAP mask;

FIG. 2 is a schematic illustration of a respiratory system in accordancewith the present invention combined with a prior art CPAP mask;

FIG. 3 is a schematic illustration demonstrating the operation of theVenturi device;

FIG. 4 is a schematic illustration of a portable respiratory system inaccordance with the present invention;

FIG. 5 is an illustration of the a novel user interface unit inaccordance with one embodiment of the present invention;

FIG. 5A is a perspective frontal view of the user interface unit of FIG.5;

FIG. 5B is a cross sectional view along line B-B of FIG. 5A;

FIG. 5C is an exploded view of the encircled area of FIG. 5B;

FIGS. 6A-6C are frontal, profile and rear views, respectively, of an airdelivering user interface unit in accordance with another embodiment ofthe invention;

FIGS. 7A and 7B are a perspective view and exploded view, respectively,of the Venturi assembly of FIG. 6;

FIG. 7C is a side view of the Venturi assembly of FIG. 7A;

FIG. 7D is a cross section along line D-D of FIG. 7C;

FIG. 8A and FIG. 8B are schematic illustrations of a bi-directionalVenturi device demonstrating air flow during inhalation and exhalation,respectively.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

The present invention provides system and method for the alleviation ofdisorders of airway block, which result in the subsequent reduction inoxygen saturation, and the attendant morbidity, by providing thenecessary air pressure to overcome airway collapse. In particular, thedevice and method described herein are intended to overcome most of thedisadvantages of present CPAP devices. However, the present inventioncan be used as a respiratory aid to treat not only sleep apnea patientsbut any patient requiring positive airway pressure for alleviation ofbreathing difficulties and airway blocks, both for assisting spontaneouspatient respiration and with modifications, for forced artificialrespiration.

The present invention replaces the conventional blower andlarge-diameter air pipe, employed in prior art CPAP systems, by ahigh-pressured compressor and an air-amplifier Venturi assembly. Assuch, the device is simple in design, light in weight, and causesminimal discomfort to the user. When used with a tank of high-pressuredair instead of a compressor, the device can be operated by batteries,eliminating the need for external power line and imparting the deviceportability. Furthermore, the present system and method allows forcontrolling of the air pressure delivered to the user according to thereal-time physiological needs of the user and can be operatedintermittently to supply positive pressure only during the inhalationphase.

Other advantages of the invention will be realized from the followingdescription.

Referring now to FIG. 2, there is described a respiratory aid system,generally designated 10, in accordance with one embodiment of thepresent invention. Compressed air produced by compressor 12, flowsthrough an optional pressure and/or humidifier 14. The air flows at highpressure of a few atmospheres through a thin flexible crush-resistantair tubing 16, preferably of 2-5 mm diameter. A fast-responding pressurevalve 18 is located between tank 14 and tubing 16, regulating the airpressure delivered to the tubing. The compressed air enters mask 15through a Venturi device 20 located at the inhalation port of the mask.The Venturi device 20, the principal operation of which is describedbelow in association with FIG. 3, reduces the high-pressure delivered bythe compressor to an acceptable desired low pressure value, preferablyin the range of 2-20 mbar, while sucking air from its closestsurroundings, i.e. from the mask vicinity, as indicated by the arrows.Venturi device 20, driven by the flow of high pressure air, functions asan air pump for both amplifying the volume and reducing the pressure ofthe air delivered to the user. Venturi device 20 is of very smalldimensions (about 8-20 mm in diameter) and can be incorporated into alltypes of currently available breathing masks without furthermodifications, providing care is taken to form an air-tight seal betweenthe external surface of the Venturi device and the inner surface of theinhalation port. In the embodiment shown here, Venturi device 20 isincorporated in the inhalation port of a conventional prior art facemask similar to the mask shown in FIG. 1.

FIG. 3. is a schematic cross sectional view of Venturi device 20demonstrating the operation of the Venturi device as an air pump.Venturi device 20 is an elongated tubular member 21 having a centralspace 22 open at both ends 24 and 25 and configured to have a throatportion 23. An annular compressed air chamber 26, having an inlet (notshown) for connecting to a tubing of compressed air, is in fluidcommunication with throat portion 23 of central space 22. The rightcorner of the junction between compressed air chamber 26 and centralspace 22 is rounded, directing air entering throat portion 23 fromcompressed-air chamber 26 to flow to the right as indicated by thearrows 27. When a flow of high pressure air from compressed air chamber26 enters into the enlarged central space 22, a suction is created, dueto the Venturi effect, entraining additional ambient air 28 from thesurrounding space to be drawn into central space 22 through open end 24toward open end 25. In accordance with the present invention, upstreamopen end 24 is in fluid communication with ambient air while downstreamopen end 25 is in fluid communication with the user airways via theinhalation port of mask 15. A particular construction of an embodimentof Venturi device 20 is described below in association with FIG. 6. Itwill be realized by a person skilled in the art that the Venturi deviceof the present invention is not limited to the particular constructiondescribed hereinabove and below and that other constructions can beused. Thus for example, it will be realized by persons skilled in theart that the throat portion 23 of central space 22 enhances theaerodynamics properties of Venturi 20 but that central space 22 may beof constant cross section.

Referring back to FIG. 2, in accordance with the embodiment describedherein, the source of the high pressure air is compressor 12. Compressor12 is preferably an oil-less compressor for avoiding oil fumecontamination of the air delivered to the user. Preferably, compressor12 is a quiet compressor, having controllable output pressure in therange of about 2-6 atmospheres. Examples for compressors that can beused with the present invention are vane air compressors such as model0211 distributed by GAST, diaphragm air compressors such as Gast DOAmodels or piston air compressors such as Gast SOA models. A tank 14 canoptionally be installed between compressor 12 and valve 18 forflattening the periodical amplitude of the compressor output pressurefor obtaining a constant output pressure independent of the cyclicoperation of the compressor. Tank 14 may further serve as a humidifyingunit for regulating the humidity of the air delivered to the user.Alternatively, the source for high pressure air may be a portable tankcontaining high pressure air or other respiratory gas. For example, thehigh pressure respiratory gas may be air enriched with oxygen or can bepure oxygen. It will be realized that in accordance with the invention,the high pressure source serves mainly as the driving force for thesystem while most of the air delivered to the user is actually ambientair drawn from the surrounding. Thus, a high pressure tank of a moderatesize can drive the system for a considerable period of time, renderingthe whole apparatus mobile, and eliminating the need for external powerlines. FIG. 4 illustrates such a mobile respiratory aid apparatus,generally designated 100, in use for assisting respiratory of patient105. Portable apparatus 100 comprises a small container of compressedrespiratory gas 112 connected by thin tubing 116 to user interface unit115 via Venturi device 120. The apparatus may further comprise acontroller 118 including a user interface for entering operationparameters and a controllable valve (not shown) for regulating the flowof gas administrated to the patient. Container 112 may containcompressed air, oxygen enriched air or pure oxygen. It will be realizedthat the weight and size of an apparatus such as shown in FIG. 4 ismainly determined by the dimensions of gas container 112, as the userinterface unit 115 (which may be of reduced size as described below),thin tubing 116 and controller 118 can be easily packed into a packageof insignificant volume and weight. In this respect the advantages of asmall, light-weight portable respiratory apparatus which may be carriedby emergency medical personnel on their body as part of the first-aidequipment, cannot be overestimated for civilian as well as for militaryapplications. For example, it was found that in cases of head injuriesand in particular traumatic brain injury (TBI), immediate ventilation toinsure proper oxygen supply may positively affect respiratorycardiovascular function, increase survival rate, accelerate recovery andreduce long-term disabilities significantly, even in cases when injuredperson do not seem to lose his/her spontaneous breathing ability. Anapparatus as of FIG. 4 can be used for immediate ventilation of theinjured person at the scene of injury and during evacuation, until theinjured person is brought to a medical facility. This is of particularimportance, for example, in military situations where a firstventilation aid can be provided to an injured soldier by the medicalpersonnel in the field. Likewise, apparatus as of FIG. 4 may be used byemergency medical staff arriving at accident scenes, or can be carriedas part of the first aid equipment during activities in unpopulatedareas, such as mountain climbing etc.

It will be realized that the apparatus described in FIG. 2 (or FIG. 4)can be used as is to replace prior art CPAP for providing continuouspositive pressure to the user. However, the new features of theinvention can be utilized for rendering the system to be far moreadvantageous as described in the following.

Due to the high pressure in tubing 16 a change of pressure at theentrance to tubing 16 immediately results in a corresponding change ofthe input pressure to Venturi device 20, unlike the prior art CPAPapparatus where the much lower pressure inside the wide-bore tubingrequires a longer time for equalizing the pressure along the tubing.This allows for a simple real-time regulation of the airflow provided tothe user by controlling the input pressure at the entrance to tubing 16.Regulation of the airflow in accordance with the user needs can be thusobtained by installing at least one sensor 19, for monitoring userbreathing and connecting the sensor to a controller which controls theinput pressure to tubing 16. The sensor may be any sensor known in theart for monitoring a breathing cycle. For example, sensor 19 may beincorporated in the user interface unit for monitoring changes inducedby inhalation or exhalation. Sensor 19 may be a sound transducer fordetecting breathing sounds, a sensitive pressure detector monitoring thedrop of pressure at the commence of inhalation phases and increase ofpressure at the commence exhalation phase by means of a sensitivediaphragm and the like, or a sensitive temperature for detectingtemperature variation such as temperature increase at the nasal orificeduring exhalation. Alternatively, the sensor may be a pneumatic ormechanical breathing belt attached to the user's chest for detectingexpansion and contraction of the chest.

The control circuit allows for regulating the positive pressure inaccordance with the user respiratory cycle such that air may bedelivered only during inhalation phase, resulting in enhanced efficiencyof the system and more importantly in greater ease and benefit to theuser. The ability to compress air only during inhalation and to stopduring exhalation considerably eases the operation of the system,especially for users in need of relatively high pressure to relieve theblockage of the pulmonary airway. Furthermore, the control circuit mayinclude a programmable microprocessor including a memory device whichmonitors the user breathing pattern over time enabling a long termcontrol of the airflow delivered to the user. Hence, during periods ofnormal non-obstructive breathing, the supply of positive pressure can beturned off completely, while upon detection of a breathing disorder, forexample by detecting a cessation of breath or a significant change inthe breath periodicity, the positive pressure is turned on. It must beemphasized that as soon as the flow of compressed gas into Venturidevice 20 ceases, the pressure inside the Venturi immediately drops toatmospheric pressure so that the Venturi device functions as a passiveopen tube of relatively large opening that does not inflict anyresistance to normal breathing. This is noteworthy in particular withregard to the ease of exhalation.

In accordance with the invention, the input pressure at the entrance oftubing 16, and consequently the positive pressure delivered to the user,can be controlled, by a number of ways. In accordance with one method,the pressure is controlled by directly connecting the control circuit tocompressor 12 for regulating the input power and consequently theoperation speed and output pressure of the compressor. According toanother, more preferable method, the output pressure of compressor 12(flattened by optional tank 14) is kept constant and the pressure iscontrolled by means of pneumatic valve 18. It will be realized that acombination of the two methods is also possible. Pneumatic valve 18 maybe an on/off valve, such as a solenoid actuated valve, or a continuouscontrollable operating valve, such as flow regulation valve. Where valve18 is an on/off valve, regulation of the pressure can be obtained in thesimplest way by keeping the valve open during inhalation phase and shutduring exhalation phase. In such a case, an additional buffering tankmay be installed between valve 18 and tubing 16 for allowing gradualbuild up of pressure during the inhalation phase and gradual drop ofpressure during exhalation. Preferably, the high pressured respiratorygas is delivered to tubing 16 via valve 18 in a pulsating manner toallow controlling the average pressure delivered to tubing 16 bychanging the frequency and duration of pulses. This allows for changingthe amplitude of positive pressure supplied to the user in a continuousmanner.

The use of a thin and very light tubing for the flow of the compressedair, instead of the prior art wide-bore tubing, allows the replacementof conventional CPAP masks by an air delivery user interface of reducedsize for enhancing the user comfort and providing a more aesthetic look.FIG. 5 depicts such a novel air delivery user interface unit inaccordance with one embodiment of the invention that utilizes the mouthand jaw structure to support the small-sized unit and does not requirehead straps. The air delivery assembly, generally designated 30, issituated between the lower jaw and the nose and is dimensioned toprotrude no further than the nose bridge. The device does not require arigid jaw closure, therefore allowing the user to close and open hismouth during sleep. Assembly 30, shown in detail in FIG. 5A, includes amouth piece 32, comprising two resilient arms 34 to be inserted into themouth of the user under the upper teeth, or embracing the upper gums,connected to two resilient arms 36 on which the air delivering unit 38is mounted such that frontal surface 39 of unit 38 is lying between noseand upper lip. Mouth-piece 32 is configured to allow the user to freelyopen and close his/her mouth. Unit 38 includes two Venturi devices 40 influid communication with high pressure inlet 42, as best seen in FIG. 5Band FIG. 5C, terminating with small conical bellows 49 to be insertedinto the user's nostrils. In FIGS. 5A, 5B ad 5C, like numbers refer tolike parts. In operation, high pressure respiratory gas is forcedthrough inlet 42 to flow through common passage 43 toward Venturidevices 40. The airflow enters the central space 47 of each of Venturidevices 40 through narrow passage 45 thereby drawing ambient air fromopening 44 to flow toward opening 46 as indicated by arrows 48, and intothe user airways.

Another embodiment of a novel user interface unit is depicted in FIGS. 6and 7. In accordance with this embodiment, tubing 52 delivering the airto user interface unit 50 serves also as the means for holding device 50in place. As can be seen, tubing 52 bifurcates via a T-connector intotwo branches 52 a and 52 b, each delivering air to corresponding nasalextension 55 via corresponding Venturi 60. Alternatively, oradditionally, tubes 52 a and 52 b may be each wrapped to form a looparound one of the user's ears for enhancing the grip between unit 50 andthe user's head and for keeping unit 50 in place. Tubing 52 is made ofcrush-resistant material for preventing occlusion of the air pathwaywhen pressure is applied on the tube such as for example by the head ortrunk of the user. Tubing 52 may be flat, comprised for example from aribbon of parallel tubes of small diameter aligned side by side, forenhancing the user's comfort.

User interface unit 50 of FIG. 6 is shown in detail in FIG. 7. Userinterface unit 50 comprises a flat elongated connector member 54 made offlexible material to be placed between mouth and nose and two Venturidevices 60 pivotally mounted by means of wings 71 on both sides thereoffor allowing adjusting distance and angle for best fitting the useranatomy. Each of Venturi devices 60 is provided with an inlet 62 forconnecting to tubing 52 delivering the high-pressure gas. Compressed airentering central space 65 through inlet 62 is directed to flow to theleft toward opening 66. The upstream end 68 is open to the surroundingambient air. As best seen in exploded view in FIG. 7B, main tube 70comprises an upstream member 72, a central member 74, a downstreammember 76 and a nasal extension 78 to be inserted into the usernostrils. The different parts are configured such that when assembledtogether a narrow annular gap is formed between parts 72 and 76 to allowflow of air from inlet 62 into central space 65. It will be realizedthat the constitution of Venturi 50 is not limited to the particularelements as described in FIG. 7B. Thus, the whole Venturi assembly maybe fabricated as a one piece or a one or more components may be combinedto form one integral part.

It will be appreciated that the combined use of the air-flowing systemas described in association with FIGS. 2 and 4 together with theproposed new interface unit as described in association with FIGS. 5through 7, allows for the possibility to twist and turn during sleepwithout waking and without interfering with the operation of the system,thus significantly minimizing user's discomfort and improving sleeppattern.

Yet, in accordance with a further embodiment of the present invention,the high pressured airflow is utilized not only as the driving force fordelivering air into the user's airway during inhalation but also as thedriving force for assisting removal of air from the user airway duringexhalation.

FIGS. 8A and 8B are schematic cross sectional views of a bi-directionalVenturi assembly, generally designated 80, in accordance with abi-directional embodiment of the invention, demonstrating the operationof the Venturi as a bi-directional air pump. Venturi assembly 80 is anelongated tubular member 81 having a central space 82 open at both ends84 and 85. Two annular compressed air chambers 86 and 88 having an inlet(not shown) for connecting to a source of compressed air are in fluidcommunication with the central portion of central space 82 throughnarrow passages 86 a and 88 a, respectively. The junctions betweenpassages 86 a and 88 a with central space 82 are configured such as todirect compressed air entering from chamber 86 to the right and todirect compressed air entering from chamber 88 to the left. Inoperation, compressed air is entering central space 82 alternately fromchamber 86 to entrain ambient air to flow to the right as indicated bythe arrows in FIG. 8A and from chamber 88 to entrain ambient air to flowto the left as indicated by the arrows in FIG. 8B. Thus, by using asimple valve which directs the compressed air alternately betweenchambers 86 and 88, the device can be once actuated for forwardingairflow into the user airways for the purpose of inhalation as describedabove, and then to reverse the airflow direction for supportingexhalation, hence to significantly relieve patients with breathingproblems. Furthermore, the possibility to use a bi-directional airpassage system and activate it to either compress and force air forwardduring inhalation, or remove air during exhalation, actually transformsthe system into a respirator breathing unit facilitating forcedbreathing.

It will be realized that although the schematic description of FIG. 8illustrates bi-directional Venturi assembly 80 to be symmetrical inrespect to its left and right portions, in reality the Venturi assemblycan be configured to have two asymmetric portions for allowing differentforced to entrained ratios. Additionally, by regulating the pressure offorced gas into the Venturi assembly, as described above, it is possibleto accurately regulate both forward and reverse airflow for best fittingthe patient needs.

Although the invention has been described in conjunction with specificembodiments thereof, it is evident that many alternatives,modifications, and variations will be apparent to those skilled in theart. Accordingly, it will be appreciated by persons skilled in the artthat the present invention is not limited to what has been particularlyshown and described hereinabove. Rather the scope of the presentinvention is defined only by the claims which follow.

1. A portable respiratory aid system for administrating a regulated flowof air to a person suffering from sleep apnea, the respiratory aidsystem comprising: a source of high pressure air; an air delivery nasalinterface comprising two air delivery units configured for delivering aflow of air each to a respective nostril of said person, the two airdelivery units being pivotally mounted on opposite ends of a flatelongated flexible member configured to be placed above the upper lip ofsaid person, wherein each of said two air delivery units comprises aVenturi device, said Venturi device comprising a hollow member defininga central space and an inlet which opens into said central space, afirst open end opens to surrounding ambient air and a second open endbeing provided with a nasal adaptor attachable to a nostril of saidperson, wherein said first inlet is configured for receiving a flow ofhigh pressure air via a thin flexible tubing and for directing said flowof high pressure air toward said second open end; and a thin flexibletubing bifurcating into two branches for delivering a flow of highpressure air from said source of high pressure air to said inlet of eachVenturi device, said tubing being configured for serving as strappingmeans for strapping said air delivery nasal interface to said person'shead; at least one sensor for monitoring breathing of said person; and acontrol unit operably connected to said at least one sensor forregulating said flow of high pressure air in accordance with saidmonitored breathing, the control unit comprising a microprocessor and amemory device configured for monitoring a breathing pattern over time,thereby enabling a real-time regulation of said flow of air inaccordance with respiratory cycles of said person and a long termregulation in accordance with said monitored breathing pattern.
 2. Therespiratory aid system of claim 1 wherein the thin tubing diameter is inthe range of 2 to 5 mm and wherein said source of high pressure air hasan output pressure in the range of 2 to 6 Atmospheres.
 3. Therespiratory aid system of claim 1 wherein said source of high pressureair is a portable container of compressed air.
 4. The respiratory aidsystem of claim 1 wherein said source of high pressure air is anoil-less air compressor.
 5. The respiratory aid system of claim 4wherein said control unit is operably connected to said oil-lesscompressor.
 6. The respiratory aid system of claim 1 wherein said atleast one sensor is a sound transducer or a temperature detector.
 7. Therespiratory aid system of claim 1 wherein said at least one sensor is apressure detector.
 8. The respiratory aid system of claim 1 furthercomprising a controllable valve operably connected to said control unit,said controllable valve is interposed between said source of highpressure air and said first inlet of the at least one Venturi device. 9.The respiratory aid system of claim 8 wherein said controllable valve isan on/off valve.
 10. The respiratory aid system of claim 8 wherein saidcontrollable valve is a flow regulation valve.
 11. The respiratory aidsystem of claim 1 further comprising a chest-mounted sensor adapted fordetecting expansion and contraction of the chest of the person.
 12. Therespiratory aid system of claim 1 wherein at least one of said Venturidevice further comprises a second inlet which opens into said centralspace and wherein said second inlet is configured for receiving a flowof high pressure air and for directing said flow of high pressure airtoward said first open end.
 13. The respiratory air system of claim 1wherein said long term regulation in accordance with said monitoredbreathing pattern comprises turning on said flow of high pressure airupon detection of a breathing disorder and turning it off upon detectionof a regular non-obstructive breathing.
 14. An air delivery nasalinterface comprising: two air delivery units configured for delivering aflow of air to one of a pair of nostrils of a person, said two airdelivery units being pivotally mounted on opposite ends of a flatelongated flexible member configured to be placed above the upper lip ofsaid person, wherein each of said two air delivery units comprises aVenturi device, wherein each of said Venturi devices comprises a hollowchamber defining a central space, and an inlet which opens into saidcentral space, said hollow member having a first open end which opens tosurrounding ambient air and a second open end provided with a nasaladaptor, wherein the inlet of each of said Venturi devices is configuredto receive a flow of high pressure air via a thin tubing and to directsaid flow of high pressure air toward said second open end, wherein saidflow of high pressure air upon entering said central space acts as adriving force for drawing ambient air through said first end toward saidsecond open end; a thin flexible tubing bifurcating into two branchesfor connecting a source of high pressure air to each of said inlets ofsaid two air delivery units, said tubing being configured for serving asstrapping means for strapping said air delivery nasal interface to aperson's head; and at least one sensor for monitoring breathing of aperson using the air delivery nasal interface.
 15. The air deliverynasal interface of claim 14 wherein said at least one sensor is a soundtransducer or a temperature detector.
 16. The air delivery nasalinterface of claim 14 wherein said at least one sensor is a pressuredetector.
 17. The air delivery nasal interface of claim 14 furthercomprising a controllable valve interposed upstream of the two firstinlets of said two air delivering units.
 18. The air delivery nasalinterface of claim 14 wherein the at least one Venturi devices furthercomprises a second inlet which opens into said central space and whereinsaid second inlet is configured for receiving a flow of high pressureair and to direct said flow of high pressure air toward said first openend.
 19. The air delivery nasal interface of claim 18 further comprisinga controllable valve operably interposed between said first and secondinlets, the controllable valve is configured for allowing direction offlow to either the first inlet or to the second inlet.
 20. A method foradministrating a controlled flow of air to a person suffering from sleepapnea, in accordance with the real-time needs of said person, the methodcomprising: connecting a portable source of high pressure air by meansof a thin tubing to an air delivery nasal interface wherein the airdelivery nasal interface comprises two air delivery units configured fordelivering a flow of air each to a respective nostril of said person,the two air delivery units being pivotally mounted on opposite ends of aflat elongated flexible member configured to be placed above the upperlip of said person, wherein each of said two air delivery unitscomprises a Venturi device, both Venturi devices, comprising a hollowmember defining a central space, an inlet that opens into said centralspace, each hollow member having a first open end that opens intosurrounding ambient air and a second open end provided with a nasaladaptor attachable to a person's nostril, each of said Venturi devicesbeing configured to receive a flow of high pressure air through saidinlet and to direct said flow of high pressure air toward said secondend, thereby drawing ambient air from said first open end toward saidsecond open end and reducing said high pressure to a pressure of lowervalue; monitoring the breathing of said person by means of a sensor; anddelivering a flow of high pressure air from said source of high pressureair via said thin tubing to said air delivery nasal interface via theinlets of said Venturi devices; and automatically regulating said flowof high pressure air in accordance with the monitored breathing so as toadminister a flow of a desired pressure to said person when an apneicbreathing pattern is detected and turning off the flow of high pressureair upon detection of a regular non-obstructed breathing.
 21. The methodof claim 20 wherein said source of high pressure air is a container ofhigh pressure air.
 22. The method of claim 20 wherein said source ofhigh pressure air is an oil-less air compressor.
 23. The method of claim20, wherein said regulating the flow of air in accordance with themonitored breathing comprises the steps of: automatically turning offthe flow of high pressure during exhalation phase; and automaticallyturning on the flow of high pressure air during inhalation phase.